Method for preparing color stable maleic anhydride

ABSTRACT

This invention relates to a method for preparing color stable maleic anhydride by passing molten maleic anhydride through a bed of alkali sulfates or halides.

O Umted States Patent l 113,622,600

[72] Inventor Ja k rna d F8 [50] Field of Search 260/346.8

Dumont, NJ. 21 Appl. No. 801,835 References Cited [22] Filed Feb. 24,1969 UNITED STATES PATENTS I451 Paw-med 1971 3,1 15,503 12/1963 Bownen260/3468 [73] Assignee Halcon International Inc.

Primary Examiner-Alex Mazel Assistant Examiner-Bernard F. Dentz [54]METHOD FOR PREPARING COLOR STABLE Attorneys-William C. Long and DavidDick MALElC ANHYDRIDE 6 Claims, No Drawings ABSTRACT: Th1slllVfilltlOl'l relates to a method for prepanng [52] 260/3463 colorstable maleic anhydride by passing molten maleic an- [5 1 1 Int. ClC074: 57/14 hydride through a bed f alkali lf or ha]ides 1 METHOD FORPREPARING COLOR STABLE MALEIC ANHYDRIDE This invention relates to amethod for preparing color stable maleic anhydride.

In particular this invention relates to a method for preparing colorstable maleic anhydride by passing molten maleic anhydride through a bedcontaining an alkali or alkali earth chloride, sulfate, bromide, bariumnitrate or silver chloride or mixtures containing two or more of saidcompounds.

Maleic anhydride is produced commercially from several principle sourcessuch as by the vapor phase oxidation of or ganic compounds such asbenzene, naphthenes, butene-l and the like. While maleic anhydride soprepared can be purified by techniques known to the art to provideessentially white maleic anhydride, it is known that upon prolongedstanding this anhydride has a tendency to discolor. Further, the rate ofdiscoloration is even more pronounced when the solid maleic anhydride ismaintained in its molten form.

The darkening of maleic anhydride upon standing and/or heating presentsproblems in its commercial utilization where the color of maleicanhydride is important. Such is the case in the paint industry forexample, wherein maleic anhydride is used in the preparation of somepaints. Therefore, there is a need in the industry for maleic anhydridewhich does not discolor to any great extent and preferably remains whiteor essentially retains its color, both upon standing as well as uponheating.

it is, therefore, an object of this invention to provide a method bywhich maleic anhydride can be made color stable, particularly uponstanding at room temperature or higher for aperiod of time, and whichdoes not discolor to the same extent as a similar maleic anhydride whichhas not been treated by the method of this invention. Still anotherobject is to provide a method by which maleic anhydride which is derivedfrom benzene, naphthene or butene-l l is made color stable. Other.objects of this invention will become clear upon reading thespecification.

DETAILS OF THE INVENTION It has been found that the objects of thisinvention are accomplished by passing molten refined maleic anhydridethrough a bed of silver chloride, barium nitrate or alkali or alkaliearth sulfates, chlorides or bromides. The molten maleic anhydride iscontinuously passed through said bed, for a time which is suificient toeffect an improvement in the effluent maleic anhydride with regard toits color stability.

The source of crude or commercial maleic anhydride which is treated bythe method of this invention has little or no effect upon the ability ofthe method to render maleic anhydride, color stable. Therefore, thisinvention is applicable to the use of maleic anhydride when prepared byany of the commercially available methods. However, the invention isparticularly applicable wherein the maleic anhydride has been preparedby the vapor phase oxidation of benzene or from butene. For example, themaleic anhydride employed in this inivention may be readily preparedfrom the procedures as described in US. Pats. Nos. 2,967,185 and2,777,860.

in accordance with this invention, the maleic anhydride to be treated isobtained from distilled or normally commercially available maleicanhydride. in the preferred embodiment of this invention, the maleicanhydride is a purified or commercial maleic anhydride which has beenobtained from the vapor phase oxidation of benzene ofbutene. Inits'broadest aspect, the maleic anhydride is passed through a body ofalkali or alkali earth chloride, sulfate, bromide, barium nitrate,silver chloride or mixtures thereof. In the preferred aspects, of thisinvention calcium chloride, barium chloride, barium nitrate or sodiumchloride is used, and especially barium chloride.

The maleic anhydride (hereinafter referred to as M.A.) is passed througha bed of the above mentioned material, while in a molten state. Thetemperature at which the molten M.A. is treated is not critical.Accordingly, temperatures may be from the melting point to the boilingpoint of M.A. (52 to 198 C.), desirably from 52 to 190 C. and preferablyfrom agent is not critical, accordingly may be 0.00l to 100 mm. but

preferably 0.1 to 10 mm. and especially 0.3 to 3 mm.

The M.A. is passed continuously through the bed of solid treating agent,such that the effluent M.A. when tested for its color stability shows amarked improvement over the untreated MA.

The treated M.A. as well as the untreated M.A. is tested for its colorstability after a heat test by the well known A.S.T.M. method. Forexample, when the treated M.A. is maintained at a temperature of l37-l43C. for 24 hours in apparatus specified in A.S.T.M. procedure No.D2280-66, its color is considerably lighter than a similar, untreated,maleic anhydride which has also been so heated. it has been found insome cases that when an untreated maleic anhydride is heated asdescribed above, it has a Platinum-Cobalt color of between 100 and 150,or more, as measured by the well known A.S.T.M. method, whereas when thesimilar, but treated maleic anhydride has been heat tested as above,Platinum-Cobalt color of approximately is obtained. It has beenspecifically found that the M.A. treated by the method of thisinvention, after heat test, has a Platinum-Cobalt color much less thanthe same maleic anhydride which has not been treated, but which has beensubjected to the same test. For the purposes of this .invention a colorstable M.A. is one which has been treated by the method of thisinvention and which has a Platinum-Cobalt color of less than andpreferably less than 80 after being subjected to the heat treatment testas described above, in contrast to a similar M.A. which without beingtreated by the method of this invention has a Platinum-Cobalt color ofover 100 and more particularly over 125.

The following examples are given by way of illustration:

EXAMPLE I A stainless steel tube of 0.62-inch inside diameter is packed"to a height of 4 inches with BaCh. 211 0 crystals, (crystal size 0.3 to0.5 mm.). Molten maleic anhydride at 60 C. is pumped upward through thispacked tube at the rate of 1000 ml./hr. (i330 g./hr.) for a period of 3hours. The first hour of flow is rejected as forecut." Thereafter,effluent at l/4-hour intervals is sequestered and samples taken fromthese cuts for heat color test. (The test is described herein above).Samples of the molten M.A. feedstock are also taken for comparativepurposes. These are designated as standards." Results of the operationare presented on the table which follows. It is evident that the processtreatment has effected a marked improvement in the heat color of themaleic anhydride.

TABLE I.OONTINUOUS TREATMENT OF MoLiE'N 1m- FINED MALEIC ANHYD RIDE BYPASSAGE THROUGH A BED OF Bac -21m Bed dimensions: 0.62 inch LD. x 4 inchlong BaCl,-2H,O weight: 36.2 g.

M.A. feed rate: 1,330 gJbr.

Residence time: 1.2 min.

Mass velocity: 1,400 lb./hr. it.

LHSV: 36.7 hrs.-

1 Number gives run time in hours: letter gives quarter hour composited(thus 3B=third hour, second quarter).

2 Standard" gave color of 20 before heat test; after (4 replicates):

Similarly when sodium chloride, barium sulfate, calcium bromide, bariumnitrate or silver chloride is used in place of barium chloride in theabove example, similar results are obtained.

Similarly when a temperature of 53 C., 100 C., 150 C. or 190 C is usedinstead of 60 C. as shown above, similar results are obtained.

Similarly when a crystal size of l to 3 mm. or 5 to mm. is used in placeof 0.3 to 0.5 mm. as above, similar results are obtained.

Similarly when an LHSV of 17.1 or 1.5 hrsis used in place of 36.7 hrsinthe above example, similar results are obtained.

Similarly when a maleic anhydride from various commercial sources isused in place of the maleic anhydride in example 1 above similar resultsare obtained.

' It should be noted that the solid treating agents can be emof alkaliand alkali earth chloride, sulfate and bromide, barium nitrate andsilver chloride and mixtures thereof.

2. The method of claim 1 wherein the temperature of molten maleicanhydride is between 52 and 190 C, the L.l-l.S.V. is between 0.1 and100, and the particle size of the treating agent is between 0.001 andmm.

3. The method of claim 1 wherein the temperature of the molten maleicanhydride is between 60 and 100 C., the Ll-lSV is between 1 and 10hrsand the particle size of the treating agent is between 0.1 and 10 mm.

4. A method for preparing a color stable maleic anhydride whichcomprises passing molten maleic anhydride through a bed of bariumchloride.

5. The method of claim 4 wherein the temperature of the molten maleicanhydride is between 52 and C., and the 'L.l-l.S.V is between 0.1 and100, and the particlesize of bari-

2. The method of claim 1 wherein the temperature of molten maleicanhydride is between 52* and 190* C, the L.H.S.V. is between 0.1 and100, and the particle size of the treating agent is between 0.001 and100 mm.
 3. The method of claim 1 wherein the temperature of the moltenmaleic anhydride is between 60* and 100* C., the L.H.S.V. is between 1and 10 hrs. 1 and the particle size of the treating agent is between 0.1and 10 mm.
 4. A method for preparing a color stable maleic anhydridewhich comprises passing molten maleic anhydride through a bed of bariumchloride.
 5. The method of claim 4 wherein the temperature of the moltenmaleic anhydride is between 52* and 190* C., and the L.H.S.V is between0.1 and 100, and the particle size of barium chloride is between 0.001and 100 mm.
 6. The method of claim 4 wherein the temperature of themolten maleic anhydride is between 60* and 100* C., the L.H.S.V. isbetween 1 and 10 and the particle size of barium chloride is between 0.1and 10 mm.